Best way to cut stainless

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Hi people,I have a project modifying a stainless commercial sink for a client.  It calls for shortening it by cutting a clean straight line through it and then welding back in place the edge which is both a stiffener and splash panel.I usually use a 4 1/2" side grinder with a cutting wheel and carefully follow a line drawn with a sharpie.  For the most part I get a nice, straight cut but it tends to have some slightly hi and low spots.  This will make fitting and welding the splash panel a little harder than it normally would be as it will produce some gaps that are not good with thin sheet metal.What technique do others use for a job like this?  When a cut is critical I will get an angle iron and clamp it down using it as a guide by following its edge with the cutting wheel.Is this about the best way to make a cut like this?  What do you think?  Attached is a picture of the project.  I will start on it later today.Thanks,Tony Attached Images
Reply:Plasma.    It goes through pretty much -any- metal.But if all you have is a zip-disk, then you use what you got.btw, if the blue tape line to the right of the sink is where the cut is supposed to be, I think that puts the sink waaaaay too close to the right-hand wall/backsplash.  Imagine standin in front of that sink and having your right shoulder up against the right wall as you try to use the sink.  Ugggh.  IMHO.  The best laid schemes ... Gang oft agley ...
Reply:A sawzall with a long enough metal cutting blade with a high tooth count, and or a circular saw with the same type blade.
Reply:A sawzall with a long enough metal cutting blade with a high tooth count, and or a circular saw with the same type blade.Let's see the results which ever method you use.
Reply:Oxy torch or plasma?Last edited by Gamble; 03-05-2012 at 03:00 PM.Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by GambleOxy torch or plasma.
Reply:oxy acetylene torch.Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Hey Thererra, I had a job come in like this a few months ago.  I used a grinder and multiple cutoff wheels, and it turned out straight and true.  I would use what you already have, using a guide as you alluded to.Gamble, oxy-acetylene won't cut any stainless I've ever dealt with.  Although if it's thin enough, you can melt it in two - very ugly and fuel-intensive.
Reply:oxy torch does not work so well on stainless, the whole stainless part makes the whole oxygen reaction (rapid rusting) not work so well, without that your pretty much just melting your way along which is not a good thing. I would use plasma if possible.
Reply:Originally Posted by ironmangqoxy torch does not work so well on stainless, the whole stainless part makes the whole oxygen reaction (rapid rusting) not work so well, without that your pretty much just melting your way along which is not a good thing. I would use plasma if possible.
Reply:Originally Posted by Gambleoxy acetylene torch.
Reply:Originally Posted by GambleI thought stainless doesn't rust?
Reply:Originally Posted by GambleI thought stainless doesn't rust?
Reply:I thought stainless doesn't rust?
Reply:I would just use a new clean cut off disc.  Plasma would be faster but I think you would have more time dressing up the cut to make a nice joint.  Also mistakes happen much faster at those travel speeds.
Reply:A cut off disc is the best bet.  I really hope those who suggested an O/A torch are joking.ɹǝʌo ǝɯ lloɹ 'sıɥʇ pɐǝɹ uɐɔ noʎ ɟı
Reply:Originally Posted by TSORA cut off disc is the best bet.  I really hope those who suggested an O/A torch are joking.
Reply:I am in the middle of a major counter top screw up.I have cut  a lot of stainless with plasma and cut off wheel on a grinder.    Plasma will do a great job if  you get the travel speed right.  If not, it can make an ugly kerf that needs a lot of grinding to clean up.I just use the cut off wheel.   If you are going to weld the end back on, I want to see it.   I have been trying to weld stainless counter top with only a little luck.   Fitup has to be PERFECT, and it still warps.   DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Plasma torch with a straight edge of some sort as a guide will give the BEST cut.  I'm constantly cutting thin stainless steel for sinks and table top benches etc... My cuts look "almost" lasered!  I wouldn't stand for a cut off wheel.  The key to using plasma on stainless is to have enough amperage output (heat) and a CLEAN (filtered & dry) air source.  I use a double redundant air filter/water separator for my plasma machine.   I'll try to find some scrap stainless and post a pic here of the cuts. Also, anyone here that recommends an oxy/ac torch for stainless, obviously has never cut stainless before.  Otherwise, he/she would know that due tithe laws of chemistry, it can't be done CLEANLY.  Don't hate.....I'm just say'n.Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Plasma cutter with GOOD tip and dry air, use a straight edge.Tim Beeker.
Reply:7" abrasive wheels in a skill saw with a angle iron straight  edge. The larger dia blade dooesnt wander like a 4"Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Plasma is NOT the best choice for this job.Some posters that recommended Ox/Ace need to take a basic course in metalworking.  A new 3' cutoff wheel will do the best job.  Best to use a scrap piece of SS angle and cut down the edge using the angle as a guide.Air plasma used on thin SS leaves a non-weldable, oxide filled edge that has to be ground off anyway.  Might as well just use the cutoff wheel.  High def, mixed gas plasma reduces the need for grinding on a plasma cut edge in SS.Gamble,When you make dumb azz recommendations like this (ox/ace) you not only show how little you know, but you also confuse some new posters.  Generally, I've found if you don't know something about a particular subject, it's better to remain silent (and read), rather than comment and appear the fool.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:I find the plasma with straight guide is much faster, straighter and only takes a second to clean up with a flap wheel which still needs to be done if cut any other. But that is what I find works better, others seem to not.Tim Beeker.
Reply:.....Last edited by AMC724; 03-05-2012 at 09:50 PM.Reason: Rude commet
Reply:Hi fellas, within an hour after I posted I went ahead and cut it in the usual way using the angle grinder and a straight edge made of some 3/8" flat bar.  The edge came out true and the end splash plate fit up real smooth.  After I tacked it (using fusion tacks) about every two inches or so, I fused the seam shut all along the bottom cut and up the splash plate to form an end cap of sorts.The surface cut tended to sag slightly in the middle when I was fitting the end piece in place.  I keep some 3/16" copper plates on hand and for stainless and aluminum work and lifted the sag into place and vice gripped it into place so I could tack it.  Overall the job went real smooth, just tedious as thin stainless requires care to cut, fit and weld.  The job took 3 1/2 hours from start to finish.David R.: these counter tops won't warp (at least they haven't on me) if you fusion weld them and keep a light hand closing up the seam and a relatively rapid pace.  The metal just flows shut over the seam and the burn through is minimal.  The end cap provides stiffening power to the seam as it holds the metal in place preventing the warping both to the counter top as well as the end piece.  The trick I think is to fusion weld it and not try and run a normal puddle and feeding it rod.I wish I would have seen you post before I started the project and I would have taken photos of the steps showing the detail of the fit up and the fusion welds.Take some scrap pieces cut into rectangles and fit them up so that they meet and leave a sort of "v" groove where they meet.  This will fill in when you strike your arc and move the puddle to close the "v" groove.  If you have it right, it almost seems to close itself and you need no rod whatsoever.I took pictures of the job but since it was night outside I had to use the flash and it tends to over flash the detail so it just looks like bright metal.  I also had to put a mounting tab on the side I cut down for mounting purposes.The client is coming tomorrow morning to pick it up and he designed the cuts so that he could fit a fridge in the space where the counter top was cut down.  The sink will but against the fridge.Finally, I was reluctant to weld the face of it as I was afraid that it would not go smooth like the back side did and that I would have to feed rod in there making a relatively big bead in the process and burning through the backside.I will recommend to the client to just get some silver silicone and do the top joint.  The color will match pretty good and the seam will not even be noticeable.I would like to market myself for more of this work as there are so many restaurants and bars here in Phoenix but I need to get one of those little 110 volt inverters and small tig setup.  On my things to do list.Thanks for all your suggestions.  I never thought of using a skill saw and fine blade.  I agree, it would not wander as easily as the 4 1/2" cut off wheel does.  Thanks,TonyPS: the client brought the sink already laid out with tape where he wanted the cut out to be made.  He said not to worry about the circular cut outs left half cut. Attached ImagesLast edited by therrera; 03-06-2012 at 12:09 AM.Reason: clarificationGlad to hear the job turned out well.The last piece of "really thin SS" (a cover panel for a marine refrig) I cut, I used a scrap piece of 1"x1"x1/8" SS as a guide.  For cutting I used a 1/16" cutting disc on a standard cutoff tool.  Kept the disc vertical along the guide and used the disc mounting screw as a depth guide.For the surface, you may want to try some .035 filler wire and use a lay wire technique.  Using the lay wire technique, you're not dipping the filler, but rather keeping it at the leading edge of the puddle and running a rather fast bead.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Matabo
Reply:Looks great.  I am still working on mine, pics later today.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by TSOR....I really hope those who suggested an O/A torch are joking.
Reply:Hello gentlemen,I think the plasma approach for this job might have been a little tricky for two reasons.1. The sink top was not a single sheet but had bends and lips to stiffen it.2. It had formed channel stiffeners that were spot welded to the bottom of the sink top making it necessary to carry the cut down past the channel flanges.  These channels ran against the cut and had to be severed in order to free the cut out.The reason the cut off wheel worked well in this case I think is because the wheel was able to make the cut on the places where the sink top was bent up and down. The wheel cut into the vertical surfaces maintaining the straight line as it went.  Then it was a matter of just moving the cut off wheel's position to continue the cut using the cut as a guide.The plasma would have required moving the guide from the flat to the vertical surfaces each time.  Not the end of the world, but time consuming.  However its speed I guess would have compensated for the extra time it took to reposition the guide.Just my thoughts on the subject.  I have never actually attempted a cut like this with a plasma, only on plate or where precision didn't matter (like cutting a part off of something).Thanks for the thoughts.  I will definitely try the skill saw approach, I liked that one.Client came by this morning and took the  sink about an hour ago.Finally, I agonized about welding the top and decided not to in order to keep the cost down.  I am familiar with the lay wire technique but never attempted it on thin stuff.  I have used it for the root pass on boiler tubes.As it was, he whined when I told him it could be a $200 job.  I charged him $150.  If I had welded the top, I would have had to take it up to the $200 mark.He was happy and said he would just caulk it.TonyLast edited by therrera; 03-06-2012 at 12:00 PM.Reason: correct an error
Reply:Originally Posted by LarryOOxy torch?
Reply:I knew what you meant, Larry.  Can't speak for anyone else.
Reply:I've seen some guys mention using a piece of SS bar as a straight edge. This is important because if you use regular steel, any carbon sparks will contaminate the stainless, right? Any other reason?IW Local 580 NY, NY
Reply:A new blade on a saber saw and some more tape to protect against the baseplate would have been what I would use on it.  Or a fresh or dedicated cutting wheel.  It's good not to mix SS with any other brushes/cutting tools used on mild steel or you will embed bits of mild steel into the stainless.  If you absolutely had to cut stainless with OAW you can use a waste plate...
Reply:Originally Posted by BlueArcI've seen some guys mention using a piece of SS bar as a straight edge. This is important because if you use regular steel, any carbon sparks will contaminate the stainless, right? Any other reason?
Reply:Originally Posted by David RIf I were to use a SS bar as a straight edge for a plasma, the bar would heat up and warp causing a curved cut.    I use a carbon steel Angle of good heft with a sheet of paper under it to guide the plasma torch.    Just take a  piece of SS stock AND WAVE  a torch over it.  Watch it move all around as you move the torch.I was told by an old welder SS is stressed on both sides of the sheet when rolled.  When one side is heated it wants to warp because of the stress.I am starting anew thread  with pics of the job I am attempting.David
Reply:David,Don't know what plasma cutter you're using, but for my Hypertherm PM 1250 I use a lot of 1/8" masonite (hardboard) for pattern cutting.  If the plasma (heat) is not destroying a masonite pattern, I don't think (and have never experienced a problem warping a SS guide) that SS guides (for plasma) are as much a problem as you're making them out to be.I think what the poster was questioning was a comment I made about using a scrap piece of 1" SS angle as a guide for a 3" cutoff wheel on cutoff tool.  Here I'm lightly touching the guide as I'm making my cut in the SS material.  Sure don't want to be doing that with a carbon steel guide on SS.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.